Aero Hunting @ WTAC

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The importance of aero

Time attack is a discipline that truly rewards balance. Every single area of a car needs to be pushed to its theoretical limits and any small change alters various other variables. It was obvious that the Australians have got the power thing down to a tee but after pacing up and down the pits at this year’s WTAC, it quickly became apparent that everyone has focused a lot of their efforts on aerodynamics. We saw this all the way back when we covered the event for the first time in 2010 but since then things have really progressed leaps and bounds, from the top teams in the Pro class, all the way to the privateers that have had to learn things from scratch. So with this in mind we decided it would be rather interesting if we concentrated on this particular aspect of Time Attack – aero. It is after all the single aspect that in the last couple of years has pushed what these wildly powerful cars can do around a track.

We called in Andrew Brilliant to offer us his observations on some of the solutions we came across. He’s the man that has played a huge part in progressing the sport, both at WTAC and back in Japan where he continues to advise some of the top teams and drivers. So to get going I thought I’d start things off with the Esprit NSX…

As Andrew points out, the design is Super GT-esque which sort of means they looked at the work Dome did in the past with the NSXs they prepared for GT500.

This is especially true on the twin dive planes set-up that’s meant to help increase downforce both in a straight line and during cornering. The rear wing too is almost Super GT-spec looking. The look couldn’t possibly fit the car any better, as underneath its skin the guys at the Suzuka tuning shop rotated the V6 90-degrees and added a Hewland transaxle sequential transmission… oh and a little force feeding for good measure. Tarzan, hired to drive the car at the event, told me he was having serious overheating issues with the rear tires with the car having so much weight over the rear wheels, not to mention the added downforce.

How big can front splitters get? Well, as the Pulse Evo shows, pretty damn massive. Looks like this is a work in progress and the team are still experimenting especially on the rear section of the extremities where it used to run gurneys. The two large fins running on each side of the splitter are something curious – maybe more experimentation.

And at the back? Again this is a good example of time attack teams taking inspiration from other forms of motorsports with the rear protruding diffuser set at a low angle in an attempt to get more area diffusion. Other additions are the rear deck lid gurney and a dual element wing, set high on adjustable mounts and a pair of aluminum stays. The car has also been widened substantially to boost the front and rear track and make use of surface airflow.

How about adding some modern thinking to older cars? There are a variety of ways to address splitters and a simple one is a thin structure…

… with tension wires to support the load. When you don’t have the limitless budget of some of the bigger teams, this sort of solution is one that will help get some results. Looks like a wood material was used, hence why added support is needed with the wires.

Andrew found it interesting how the guys at Grumble Bee Motorsports recessed the front fenders behind the tires on their R31 to help with out flow and added steeply raked canards…

… and a splitter to cover the basics. Here we see adjusters being used for support rather than cables.

Different takes

Aside from the rather large diffuser, it was the end plates on this R32’s rear wing that caught my attention. They almost look like something out of the endplates of an airplane; a wild idea this team was obviously trying out. Learning by trying is one of the best ways to figure out this black art.

Certainly looks dramatic out on track!

Of course there are a bunch of aftermarket parts that are available for popular time attack cars like the BNR32 as shown here by the front section on this GT-R. Some additional openings have been drilled out for cooling and small canards fitted as basic touches.

One of the most interesting aspects on the wild-looking Tilton EG Civic is how they sculpted the rear portion of the front wheelhouses trying to help flow out behind the tires.

Up front they came up with an elegant way in which to integrate and support the canards, making them sort of merge up into the curvature of the widened and custom fenders

It’s not often that you see a ducted intercooler set-up on GT-Rs like the one shown here on Danh Tranhs BNR32. By eliminating the stock cross sections of the chassis, lots of space has been freed up allowing the intercooler to make full use of the ducted airflow and then dumping it through the hood.

Not easy to miss at the rear is the double deck rear diffuser and sculpted side skirts to aid flow out of the front wheelhouses. And yes, the wing is rather humongous!

Rear wings have continued to grow visually over the last few years in time attack and this double element one fitted to the Morepowa RPS13 is one of Andrew’s own designs.

Again a good example of addressing aerodynamics in a good way by using what is out there on the market, like the vented front fenders on this R32 GT-R.

Pushing the unknown

I was glad to see that I wasn’t the only one interested in this particular S15 – by far the cleanest out on track, probably due to the fact that it had no graphics or sponsors ruining its custom one-off sculpted body. Andrew liked this car not only for its successful use of Super GT solutions but also because it was evidently generating a good deal of downforce, noticeable thanks to suspension compression when at full speed down the main straight.

This Silvia, that you will be seeing a feature on soon, was running Voltex canards up front and the same Voltex wing as the Tilton Evo. A very nicely put together car by a team of two dedicated brothers.

Some obvious inspiration taken from Loeb’s Pikes Peak Peugeot 208 right here.

Here’s a quick look at the rear of the Bacchus/Novel ISF and its single element rear wing with chassis-mounted stays to distribute downforce directly to where it needs to go. This balances out the front splitter and canard set-up we saw in yesterday’s post.

Andrew explained that the Mighty Mouse was designed by Barry Lock. Barry is a former McLaren engineer and his designs often feature this side front wing concept. He is the man behind the MCA Hammerhead, so this is a common feature of his, including Mick Sigsworth’s car that won the Pro Am class this year.

Along the sides of the CR-X we see a creative use of the air gap between the side skirt and the chassis to draw more air out of the front wheelhouse.

Around the rear is probably the most interesting aspect of the little Honda, the wing-element-shaped upright in the center to support the wing. This is to reduce the drag of the wing support.

The interaction of canards and splitter end plates, as well as gurneys (not shown here), all need to interact with the design of other aspects of the car around them. What sometimes works, might work against you.

The use of little stepped sponge inserts from the canard to the overfenders on the Daihatsu Charade was something that was rather interesting to both myself and Andrew. Maybe the owners of the car can shed some light on this curious solution.

Fierce competition

Back on the rear side of the Charade, I particularly liked the arched diffuser. Andrew has seen many takes on this design and its effectiveness needs to be looked at on a case-by-case basis because, surprise surprise, aerodynamics are a little complex.

Here is a look at the complexities of the inner front diffuser/splitter assembly Voltex developed for the Tilton Evo. It’s similar in shape and design but probably not as extreme as the one used on Nemo. Notice all the metal supports needed to distribute and resist the load the assembly produces at speed.

Here’s a side view of the diffuser, where you can see how wide it is. And check out the F1-style end plates.

On the rear side of the side skirts I noticed an additional curved winglet was added, probably a detail Nakajima-san at Voltex is testing out in competition.

We can trace this underfloor design all the way back to 2010 when Voltex experimented with it on the Cyber Evo to increase front wheelhouse outlet volume. This evolution fitted to the Tilton looks bigger and wider. Aero is definitely all about evolution and lots of trial and error, even if you have a wind tunnel at your disposal like Voltex has.

Big wing loads necessitate big supports! Pretty simple right?

The original front wing car, the MCA Hammerhead. It’s actually a clever solution and a quick way to make some front downforce. Back when I first saw this car I thought it was almost dangerous simply due to its proportions, but then again Time Attack is all about the extremes.

Yes, extremes!

Here’s another example of Voltex carbon canard use; off-the-shelf items that can be applied in a variety of applications. Notice the carbon endplates added to the sides of the splitter.

Of course aerodynamics also takes into consideration the airflow a car needs to either cool components, or feed the engine or turbo with air. Of course on a car purely built for track use, headlights can double up as great ways of swallowing up air.

We’ve seen various takes on the front end sculpting that some use to help air flow out of the wheelhouses; here is how Voltex have done it on the Top Fuel S2000…

… and at the rear. Andrew tells us that this can also reduce drag compared to a flat, square section behind the tire.

Andrew also went on to say that typically you need some kind of a square edge to help make diffusers stronger against vertical loading, but this can also pick up some downforce just like a gurney does on a wing.

As Mr. Brilliant further elaborated when looking at the RE Amemiya Hurricane, is that they also went for the super long diffuser in an attempt to increase downforce. Their body started as a GT300 one, which while winning championships in its own right is optimized for low power and low drag. However in the time attack game, the power is much higher than in GT300 and so is the downforce.

This is pretty much all GT300 spec stuff except for the addition of the extended front splitter…

… of which you can get a much better look at from this angle. This addition would have no doubt necessitated some substantial modifications underneath to hold up to the increased load.

This is Andrew’s baby so I’ll let him talk now:

“Nemo’s canards were actually a last minute fab job, but they were shockingly effective. A single large canard placed high gave maximum effective results. Worth noting that the intercooler actually protrudes forward from the front bumper and the hood louvers and radiator outlet ducting are quite large compared to others.

“This is a good angle to see the sculpting work that was done to Nemo’s front fenders to create large outlets there. The recessed front doors were also something that Tilton used this year. Other unique features on Nemo are the large flat rear spoiler under the main rear wing and the large tunnels rather than a diffuser.”

The front splitter shape on the Team Autotech Hulk is the work of Scott Beeton, formerly of Williams F1, in Australia with a company called AERODESIGN.

I’ll finish up with one final image of the Top Fuel S2000 in action showing off that massive straight span, dual element wing developed especially for this year’s event.

I hope you enjoyed taking a closer look at the aero elements that help make time attack what it is. Special thanks has to go to Andrew Brilliant for his usual insight into this complex world of air management!

@ JDMised How about enjoying the article for what it is, a look at the many and varied things people try to get that extra bit of downforce, instead of constantly . trying to belittle the author. Are you an expert on the matter? Where's your blog/article on the way of aerodynamics?

JDMized reno808 Its really hard to know for a fact how most of this stuff performs without actually testing it yourself. Dino asked me for my thoughts and I can only comment so far as I know from having tested them or something similar. So the comments have to stay fairly general or I would be stretching my professionalism.

JDMized speedhunters_dino Dude, clearly you have issues with the author, but rather than resorting to personal attacks why not argue a point within the article that you feel is inaccurate. This will give the author a chance to reply or correct it if need be. Otherwise your comments are pointless and, more importantly, irrelevant.

Andrew I appreciate your comment and I wish (instead of having a bunch of cars featured and put into the same box, so to speak), broke it down one by one, and maybe having people like you chime in with hard data instead of speculating.

JDMized Clearly this is not meant to be a technical article and it's not labelled as such. The only waste of bandwith I see here is your anonymous trolling. Kinda regret replying to this already because by doing so I'm only giving your comments validity which they really don't deserve. over and out.

PaulDYuen The highest speed we have seen this year down the main straight was 292kph. This is down on last year where we've had a couple of cars breaking the 300kph mark. Andrew may correct me on this but big aero at the front does limit your top speed especially at such a long straight that we have at SMSP. However, the beauty of a well designed aero package is that you more than make up for that around the rest of the track.

In regards to the Pule evo, the orange evo in the first chapter. Those fins on the splitter were holding up another small wing. It fell apart around the track. My friend captured it on video here: http://www.youtube.com/watch?v=iak6aF4ELW4

3nigm4 Alex...I'd love to do a one car break down, that would be a great idea, but I don't think I know anyone out there that would be willing to share hard facts on the personal research they do on aero, especially the big teams. Plus unless we stick a car in a wind tunnel and test each aspect of it with respect to other parts on the car it would probably never quench your thirst for "hard facts" as you put it.

Skilfil JDMized speedhunters_dino Alex, super idea as usual. Maybe if I had the whole event to do so I would have talked to each team featured above and asked them questions on each detail. It all comes down to time

roryfjohnston speedhunters_dino Yes the Japanese are a bit behind on this. Maybe they will see what is out there at events like WTAC and see the results that Under Suzuki is getting and invest more into it

speedhunters_dino Like Andrew said, I am not asking him (or you) to reveal data that could compromise your/his job, but generalizing on the aero stuff for all the cars featured above is (in my opinion) pointless. Mainly because each shape of each car requires a very specific aero to work at its potential, and I don't think that asking the teams to share THEIR thoughts in regard their aero is inappropriate.If you tell me you had no time, I am sorry and I apologize for coming off as a dick. On the other hand, if you had time it would have been sweet (IMO) to see each car's aero in detailed, and maybe have Andrew chime in as much as possible (w/o compromising his professionalism).So, sorry again.

JDMized speedhunters_dino There is no generalizing here, it's called keeping it simple showing how things may work and where the idea may have come from and why it was taken. Since you obviously have an interest in this sort of stuff you will know the complexities of it all are effected by countless variables so even if we had stepped it up a notch with Andrew on the analyzation side of things, it would have still had an element of guesswork there as obviously without testing each part and getting hard facts & figures everything would still be down to Andrews on views and opinions (again as you put it). Hope that makes sense.

JDMized Seriously dude bout time you found another website and author to have a go at all the time. speedhunters_dino great article don't think anyone else is expecting you to go all aero engineer on us.

As for the Daihatsu Charade, I'm guessing the thought behind the stepped foam insert on the canard was probably an effort to quickly and cost-effectively smooth the transition from the canard to the over-fender. I probably would have left the over-fender cut where it is, moved the canard up to it, and paid more attention to diverting air away from the front of the tire. I'm curious as to whether just leaving a flat sheet of aluminum in front of the tire would be more effective in reducing drag. The flat plate, in conjunction with the splitter, should cause the air to stall, and produce downforce, as well.

Is aero like ground effect? also in the good days of F1 (ha) there was a car nick named the fan car, to bend the rules on down force usage Gordan murry ??? used a very over sized cooling fan at the rear to suck air from under the car there by sucking it to the road. It was so successful it was banned (it's F1 for god sake push the boundaries ! don't ban them) he claimed its only use was cooling but nope. they stopped it in the end because some other racers complained of being hit by stones etc sucked up by the fan car. would that be illegal in time attack? what are the rules. wonder what would be the top speed reduction with all that aero, I under stand it not land speed racing but interesting nun the less. any way great picks fantastic motors.

2bAUS JDMized speedhunters_dino Lol, you can always rely on JDMized to bring the dick element.

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